In vivo embryonic expression of laminin and its involvement in cell shape change in the sea urchin Sphaerechinus granularis

Abstract

Laminin, a component of the embryonic sea urchin basal lamina, is recognized by monoclonal antibody BL1 (Mab BL1). Our results demonstrate that laminin is secreted into the blastcoel at the early blastula stage at a time when the blastomers undergo a cell shape change and are organized into an epithelium. Laminin is present on the basal surfaces of ectodermal cells and is absent or reduced on migrating primary mesenchyme cells. Mircroinjection of a monoclonal antibody directed against laminin induces a morphological change in cell shape and a deformation of the embryonic epithelium. Investigation of selected stages of live embryos suggests that the distribution of laminin may be heterogeneous within the basal lamina during early development. The results implicate laminin as a mediator of cell shape change during early morphogenesis.